Gun for perforating casing



y 7, 1953 w. E. KANADY 2,644,519

GUN FOR PERFORATING CASING Filed Sept. 11, 1950 23 a M M, 24 I4 I I I6 a 25 r I? I7 i 26 I7 I E: I7 26 3;? 25

INVENTOR.

William E. Kanady,

A TTORNEY.

Patented July 7, 1953 UNITED stares ENT OFFICE.

GUN FOR PERFORATING CASING of Delaware Application September 11, 1950, Serial No. 184,169

'7 Claims. (Cl. 1640.5)

This invention relates to guns for perforating pipe in oil wells or the like and more particularly to guns which are small enough to run through tubing in a well for perforating casing beneath the tubing.

Guns and explosives have long been used for perforating casing in oil wells and the art is well developed. As commonly constructed the barrels of guns used for such purposes approach in length, as far as is practical, the diameter of the casing so as to obtain the maximum fire power. Even under the best conditions, effective perforation of oil well casing and the cement which usually surrounds it, is diificult to accomplish, and since the size of the gun or explosive is important, casing perforators as con" ventionally used have not been run into the well through tubing or other pipe smaller in diameter than the casing.

It has recently been proposed to perform certain operations including the perforating of casing in an oil well while tubing is in it. See for example application of Theodore A. Huber, Serial No. 133,025, filed December 15, 1949, for Method of Completing and Repairing Oil Wells where the use of a casing perforating gun capable of being run through tubing is required. Large savings in time and cost can be effected in this way if effective perforation can be accomplished.

In accordance with application Serial No. 184,161 filed by Theodore A. Huber, it is proposed to solve the problem of providing effective firing power to perforate casing with an assembly which is run into and out of the well through tubing by arranging the guns in their carriage on trunnions and by providing means for rotating them from the vertical positions which theyoccupy while being lowered into the well, into horizontal firing positions. Inasmuch as the guns may be fired by electricity, Huber proposed to employ an electric motor to rotate them exactly the right amount.

The present invention relates to a specific arrangement for rotating the barrels in the Huber type of perforating gun. Instead of using an electric motor, hydrostatic pressure is used to bring about the desired rotation from the vertical to the horizontal position. After firing the gun, the barrels may be returned to their vertical position under the action of a spring.

The objects of the invention will be apparent from the following description, taken in connection with the accompanying drawing in which:

Fig. 1 is a vertical cross-sectional fragmentary view of casing and tubing in an oil well with a gun constructed in accordance with the present invention located therein.

Fig. 2 is a vertical cross-sectional view of a portion of the gun of Fig. 1, the view being taken at a right angle to that of Fig. 1.

Referring to the drawing in detail it will be seen that casing of an oil well is there shown at I2. It is this casing which is to be perforated. Tubing I3 is positioned in the well with its lower end above the portion of the casing I2 which is to be perforated, as shown in Fig. 2.

Within the tubing I3 is an elongated gun body or carriage I4 which is lowered into the well on an electric cable I5. The carriage 14 may be made of steel and is of cylindrical shape and it is smaller in diameter than that of the tubing run into the well through the casing I2.

Perforating gun barrels I6 are mounted in the carriage I4 on trunnions I1 and the arrangement may be such that all point in the same direction (to the left as viewed in Fig. 1) when they are fired. Each barrel I6 is of a diameter less than that of the tubing I3 and of a length greater than the diameter of the tubing but less than the diameter of the casing I2.

As shown, the carriage I4 is provided with spaced slots I8 to accommodate the barrels I5 and permit them to rotate on their trunnions over an arc of degrees, as indicated by the dashed-line arrows in Fig. 1. When the gun is being lowered down through the tubing, all of the barrels I6 are in their vertical positions longitudinal of the carriage I4, and, in the form shown, all of the guns are pointing upwardly. It will be understood that if one gun is pointed upwardly and the next downwardly when in their vertical position, they will fire in opposite directions when brought into their horizontal positions and make staggered perforations in the casing I2.

To rotate the barrels I6 into their horizontal, firing positions transverse of the carriage I4, in accordance with the present invention, hydrostatically operated means is employed and preferably this means is responsive to the difference in fluid pressure between the inside and outside of the tubing I3. To this end, the head 20 of the carriage I4 may be provided with a cylindrical bore 2I in which a piston 22 is fitted. Of course, a bellows or diaphragm type of pressure responsive device could be used in place of the piston and cylinder; The piston rod 23 extends downwardly and is integrally connected to a yoke 24 which passes along side the barrels It. The trunnions I! are provided with pinions 25 in mesh with racks 26 in the yoke 24, so that all the barrels I6 rotate simultaneously. A coil spring 21 is located between the bottom of the 'yoke 24 and the lower end of the carriage I4 so as to urge the yoke upwardly against the fluid pressure exerted on top of the piston 22. A dash pot or the like could be used instead ofthis spring, as will be obvious to those skilled in the art.

The head 20 of the carriage I4 is so designed that fluid pressure can be exerted on the piston 22 only when the gun is in position beneath the lower end of the tubing in the well bore. The tubing I3 has an internal ring 28 for forming a seat at its lowerend and the head 20 is provided with a flange 29 which makes a fluid tight seal with the ring 28. fluid in the tubing is admitted to the chamber 2|, and when the gun is located as shown in Fig. 1, an increase in fluid pressure in'the tubing I3 will cause the piston 22 to move downwardly. Fluid beneath the piston 22 can escape from the cylinder through ports 32 and 33.

The barrels I 6 may each have a powder chamber 34 and be fired by a fuse 35 as shown in dotted lines in the upper barrel of Fig. 1. To insure Through ports 30 in a cap 31,

against accidental discharge, the circuits to the I To operate the gun, it is lowered down through the tubing 13 until the head M comes to rest on the ring 28. The firing circuit for the guns may then be closed at the surface of the ground and fluid pressure exerted in the tubing, as by pump pressure. When the piston 22 moves the yoke 24 downwardly, in response to the difference in pressure inside and outside of the tubing, the racks 2B rotate the barrels IS in a counter-clockwise direction, as viewed in Fig. 1, over an arc of 90 degrees, closing the switches 363'I and causing the guns to fire and perforate the casing.

If the pressure inside the tubing 13 is then relieved, or if the gun carriage I4 is raised slightly to lift the head 20 011 of the ring ZS, the spring 2'! acts to rotate the barrels I6 back into their initial vertical position so that they can be retrieved through the tubing I3.

It is within the purview of the invention to' dispense with the cable I5 and merely drop the gun into the tubing or pump it down. Firing could be controlled by mounting firing pins in thegun body M in place of the electrical contacts 3! and cause them to strike, with spring pressed trigger release or otherwise, percussion caps mounted on the barrels in place of the buttons 36. Various other changes may be made without departing from the spirit of the invention or the scope of the annexed claims.

I claim: v

1. A device for perforating casing in an oil well below tubing suspended within said casing comprising an elongated carriage, a plurality of gun barrels having trunnions for mounting them individually for rotation in said carriage, said trunnions having pinions thereon, a yoke extending longitudinally of the carriage and having racks in mesh with said pinions and hydrostatic pressure operated means for actuating said yoke to rotate the barrels simultaneously from their vertical positions longitudinal of the carriage into positions transverse thereof, whereby, after the barrels have passed beneath the lower end of the tubing, they may be brought in to horizontal position and fired.

2. The device defined in claim 1, in combination with a spring which opposes the action of said hydrostatic pressure operated means and which causes the barrels to return to their vertical positions when the hydrostatic pressure is relieved.

3. A device for perforating casing in an oil well below tubing suspended within said casing comprising a carriage, a gun barrel having trunnions for mounting it for rotation in said carriage; hydrostatic pressure operated means mechanically connected to one of said trunnions for rotating said barrel from its vertical position longitudinal of the carriage into a position transverse thereof, whereby said carriage may be moved downwardly in said tubing and, after the barrel has passed beneath the lower end of the tubing, it may be brought into horizontal position and fired.

4. The device defined in claim 3, in combination with a spring which opposes the action of said hydrostatic pressure operated means and which causes the barrel to return to its vertical position when the hydrostatic pressure is relieved.

5. The device defined in claim 3 in combination with an electrical firing switch closed on contacting an electrical contact mounted on said carriage upon the rotation of the barrel to a position transverse of the carriage.

6. The device defined in claim 1 in which said hydrostatic pressure operated means includes a piston and cylinder located in a head on said carriage, said head having a sealing surface exteriorly thereof, whereby said head is adapted to engage matingly with a surface positioned adjacent the lower end of the tubing to form a seal between said head and said tubing and the barrels can be rotated into firing position in response to the diflerence in pressure between the inside and outside of said tubing,

'7. The device defined in claim 3 in which said hydrostatic pressure operated means includes a piston and cylinder located in a head in said carriage, said head having a sealing surface exteriorly thereof, whereby the sealing surface on said head is adapted to engage matingly with a WILLIAM E. KANADY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,013,457 Burt Sept. 3, 1935 2,326,405 Spencer Aug. 10, 1943 2,543,814 I Thompson Mar. 6, 1951 

